Software update: MySQL 4.0.9 gamma

MySQL is rapidly releasing new updates to its popular database server. MySQL is designed to be simple, fast and reliable. However, this has prevented a number of complicated commands from finding their place in the ever-growing list of SQL statements supported by MySQL. The latest version of MySQL is 4.0.9 which has been flying over the web for five days now. Here’s what’s changed in this release:

Functionality added or changed:

• OPTIMIZE TABLE will for MyISAM tables treat all NULL values ​​as different when calculating cardinality. This helps in optimizing joins between tables where one of the tables has a lot of NULL values ​​in a indexed column: SELECT * from t1,t2 where t1.a=t2.key_with_a_lot_of_null;
• Added join operator FORCE INDEX (key_list). This acts likes USE INDEX (key_list) but with the addition that a table scan is assumed to be VERY expensive. One bad thing with this is that it makes FORCE a reserved word.
• Reset internal row buffer in MyISAM after each query. This will reduce memory in the case you have a lot of big blobs in a table.

Bug fixed:

• A security patch in 4.0.8 causes the mysqld server to die if the remote hostname can’t be resolved. This is now fixed.
• Fixed crash when replication big LOAD DATA INFILE statement that caused log rotation.

MySQL/InnoDB-4.0.9, January 14, 2003

• Removed the warning message: ‘InnoDB: Out of memory in additional memory pool.’
• Fixed a bug: if the combined size of InnoDB log files was >= 2 GB in a 32-bit computer, InnoDB would write log in a wrong position. That could make crash recovery and InnoDB Hot Backup to fail.
• Fixed a bug: index cursor restoration could theoretically fail.

MySQL/InnoDB-4.0.8, January 7, 2003

• InnoDB now supports also FOREIGN KEY (…) REFERENCES …(…) [ON UPDATE CASCADE | ON UPDATE SET NULL | ON UPDATE RESTRICT | ON UPDATE NO ACTION]†
• Tables and indexes now reserve 4% less space in the tablespace. Also existing tables reserve less space. By upgrading to 4.0.8 you will see more free space in “InnoDB free” in SHOW TABLE STATUS.
• Fixed bugs: updating the PRIMARY KEY of a row would generate a foreign key error on all FOREIGN KEYs which referenced secondary keys of the row to be updated. Also, if a referencing FOREIGN KEY constraint only referenced the first columns in an index, and there were more columns in that index, updating the additional columns generated a foreign key error. These bug fixes will only be backported to 3.23 if users find this a big problem.
• Fixed a bug: if an index contains some column twice, and that column is updated, the table will become corrupt. From now on InnoDB prevents creation of such indexes.
• Fixed a bug: removed superfluous error 149 and 150 printouts from the .err log when a locking SELECT caused a deadlock or a lock wait timeout.
• Fixed a bug: an assertion in btr0sea.c, in function btr_search_info_update_slow could theoretically fail in a race of 3 threads.
• Fixed a bug: one could not switch a session transaction isolation level back to REPEATABLE READ after setting it to something else.

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